This invention relates to an electrode material, particularly an electrode material of light weight having high energy density as well as high maximum output density, which can provide a non-pollutative battery.
In recent years, with the progress of electronics, it has been earnestly desired to develop a battery of new type, which is light in weight and compact, having high electromotive force, high maximum output density and high energy density.
In the prior art, it has been reported to use a carbonaceous material for an electrode. For example, it is reported that, when Li metal is used for a negative electrode and graphite for a positive electrode, BF.sub.4.sup.-, C10.sub.4.sup.-, I.sup.-, etc. can be doped between the graphite layers by charging and dedoping can proceed by discharging, thus obtaining reversibility of charging-discharging. However, the increase of the anions electrochemically doped is limited by the material repellency of the anions doped between the layers, and also no great energy density can be expected, with the energy density being as low as aobut 100 wh/kg.
On the other hand, when graphite is used as the negative electrode, cations such as Li.sup.+ ions can be doped between the layers, but they are very instalbe in an electrolyte and also react with the electrolyte, thus providing only an unsuitable electrode material (Surface 21 (1) 2 (1983); Electrochemistry 46, 438 (1978); Journal of Electrochemical Society, 125, 687 (1978)).
It is also reported to utilize active carbon fibers as the electrode material for both electrodes, but the electromotive force is as low as 1.2-2.9 V, the maximum output and energy densities are also small and self-discharging after charging is a problem (Japanese Unexamined Patent Publications Nos. 35881/1983 and 149654/1984).
There is also a report about use of a polymer sintered product comprising carbon as the main component obtained by heat calcination of a polymer as the electrode material for both electrodes. However, the electromotive force obtained is as low as 1.2-1.4 V, and the short circuit current is unsatisfactorily as small as 30 uA to 4 mA (Japanese Unexamined Patent Publication No. 93176/1983).
Further, there is also another report about use of an electroconductive polymer such as polyacetylene, poly-p-phenylene as the electrode material. When polyacetylene is used for both electrodes, the electromotive force is 2.5 V, the energy density 150 wh/kg and the maximum output density 17 K.W./kg. When Li metal is used for the negative electrode and a polymer electrode only for the positive electrode, the electromotive force is 3.5 V, the energy density 290 wh/kg and the maximum output density 35 K.W./kg. Thus, performances as a battery can be exhibited (Solid Physics 17(12), 753 (1982), Japanese Unexamined Patent Publication No. 112584/1984) However polyacetylene is unstable and very susceptible to oxidative deterioration. the result is a poor performance of the battery such as cycle life, etc. Also, since polyacetylene, poly-p-phenylene, etc. are insoluble and infusible, and therefore they can be worked with difficulty and cannot be formed into various forms of electrodes.